Five types of enzymes are known, having an activity to transfer N-acetylglucosamine to a non-reducing terminal of Galβ1-4Glc or Galβ1-4GlcNAc group through β1,3-linkage, which activity is involved in the synthesis of polylactosamine sugar chains (Togayachi, A. et al., J Biol Chem, 2001, 276, 22032–40; Shiraishi, N. et al., J Biol Chem, 2001, 276, 3498–507; Sasaki, K et al., Proc Natl Acad Sci USA, 1997, 94, 14294–9). However, although the amount of polylactosamine on cell surfaces is increased by making the cells express the gene of the enzyme, some of the enzymes expressed have very low activities. Thus, although it is thought that the enzymes which produce polylactosamine have different characteristics, the characterization of the enzymes has not been sufficient. Therefore, to prepare or produce the polylactosamine sugar chain structure which requires the enzyme activity, it is necessary to chemically synthesize the structure, isolating the structure from a biological component or to synthesize the structure enzymatically using a tissue homogenate.
It is known that sugar chain structures such as Lewis antigen exist on the sugar chain structures based on polylactosamine sugar chains (Kannagi R. Glycoconj J. 1997 August; 14(5):577–84. Review; Nishihara S et al., J Biol. Chem. 1994 Nov. 18; 269(46):29271–8). Similarly, it is said that the structures such as the lengths of polylactosamine sugar chains are involved in cellular immunity by NK cells or the like (Ohyama C et a., EMBO J. 1999 Mar. 15; 18(6):1516–25). Similarly, it is known that human stomach tissue is infected with Helicobacter pylori through a related sugar chain such as Lewis antigen (Wang G et al., Mol Microbiol. 2000 June; 36(6):1187–96. Review; Falk PG et al., Proc Natl Acad Sci USA. 1995 Feb. 28; 92(5):1515–9). Thus, if the gene of an enzyme having an activity to transfer N-acetylglucosamine to a non-reducing terminal of Galβ1-4Glc or Galβ1-4GlcNAc group through β1,3-linkage can be cloned, and if the enzyme can be produced by a genetic engineering process using the gene, an antibody to the enzyme may also be produced. Therefore, these are useful for the diagnoses, therapies and prophylactics of cancers, immune diseases and infectious diseases by pylori. However, the enzyme has not yet been purified or isolated, and there is no clue to the isolation of the enzyme and identification of the gene. As a result, an antibody to the enzyme has not been prepared.